Torque Limiters

Side view of a torque limiter

The torque limiter is a protective device that limits torque transmitted in a drive system by slipping when a preset value is exceeded as a result of shock load, overload or machine jam. It automatically re-engages when the overload is removed, no setting being required. Torque is transmitted by spring loaded friction faces, the value being preset by adjustment of the spring force by simple setting of the adjustment of the nuts and bolts.

It’s suitable to use with

  • sprockets
  • Gears
  • pulleys or
  • a flange plate as the centre member clamped between the friction facings.

Our low cost protection devices range includes:

  • the original Torque limiters for an economical and durable solution and 
  • the Sheargard range for more accurate torque control and shaft synchronisation.

The Original Torque Limiter Torque Limiters and Couplings

The Torque Limiter utilises spring loaded friction surfaces for its operation; slip torque is preset by adjustment of the spring force. The Torque Limiter can be used with a sprocket, gear, sheave or flange as the centre member clamped between two friction facings. Offered complete with a range of specially machined platewheels and shaft to shaft couplings, with torque range 3 – 8540 Nm.

Metric Series Torque Limiters

To extend the range of torque capability a new series of Torque Limiters is offered providing both smaller and larger sized units with a range of 1.5 to 10,000 Nm. These units are all to metric dimensions, and as with the original series are available with a roller chain coupling for shaft to shaft connection.

Torque Limiter combined with Roller Chain Flexible Coupling

The Torque Limiter Coupling combines overload protection with ability to connect in-line shafts. The unit consists of a standard Torque Limiter and platewheel connected to a special coupling sprocket by duplex Roller Chain. Available in eleven standard sizes, they are easy assembly units providing protection and reliability.

Torque Limiters Platewheels

Cross+Morse recommend and offer as stock items specially machined platewheels for use with Torque Limiters. Both faces of Torque Limiter Platewheels are machined to 1.6μm surface finish. Uniform surfaces and parallel faces ensure that Torque Limiters will reliably maintain correct torque release and re-engagement. For the most economical drive design, select a platewheel from the increased range of standard stock platewheels.

Sheargard Overload Clutches Sheargard Clutches and Couplings

The design of the Sheargard Clutches provides for the transmission of high torques (up to 125,000 Nm) with a compact, low inertia unit. Standard stock products enables prompt delivery, at low cost of shearpin chain sprockets and flexible shaft couplings. The provision of an optional motor monitor plate enables disconnection of the power supply and/or operation of alarm signals in the event of an overload when used in conjunction with a limit switch or proximity switch.

The basic advantages of the well proven wedge shearpin, have been combined with a clutch designed for economic production, with component parts sized to enable the use of the existing range of torque limiter platewheel and chain flexible coupling to enable supply from stock of complete drive assemblies. For higher speed applications a rubber coupling is available.

Sheargard Flexible Couplings

Sheargard Chain Couplings

The standard Cross Sheargard unit combines with the Chain Coupling to provide stock overload couplings with minimum backlash and a high reliability. This construction provides a simple, reliable, easy to assemble flexible coupling capable of transmitting high loads and accommodating shaft misalignment with continuous overload protection. Motor monitor assemblies can also be used to switch off power in the event of an overload.

Sheargard ES & KE Couplings

For high speed drives (over 500 rpm) low inertia rubber elastic couplings are offered to enable quiet operation with torsional elasticity to damp vibration and absorb shock loads. The ES Couplings consists of two close grained cast iron jaws with hard rubber drive elements interposed between them, retained by a reinforced thermoplastic cap. The KE Coupling also has close grained cast iron jaws with a Pebax Polyester elastomeric gear ring interspaced to damp vibration and torsional loads. This series can be provided with taper-bore bushes on the coupling end. The KE Coupling provides a lower cost solution.